Episode 168.0 – Lyme Disease - a podcast by Core EM

A review for the emergency physician of this common tick-borne illness.

Hosts:

Audrey Bree Tse, MD

Brian Gilberti, MD







https://media.blubrry.com/coreem/content.blubrry.com/coreem/Lyme_Disease.mp3







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Tags: Infectious Diseases











Show Notes

Episode Produced by Audrey Bree Tse, MD



Background



* Most common tick-born illness in North America

* Endemic in Northeast, Upper Midwest, northwest California

* 80% to 90% in summer months



Pathophysiology



* Ixodes tick (deer tick) has a 3-stage life cycle (larvae, nymph, adult) & takes 1 blood meal per stage

* Deer tick feeds on an infected wild animal (infected with spirochete Borrelia burgodrferi) then bites humans

* On humans, they typically move until they encounter resistance (e.g. hairline, waistband, elastic, skin fold).  It takes 24-48 hrs for B. Burgdorferi to move from the tick to the host

* Pathogenesis: organism induced local inflammation, cytokine release, autoimmunity

* No person to person transmission



Clinical Presentation

Stage 1: Early



* Symptom onset few days to a month after tick bite

* Erythema migrans rash: bulls eye rash seen in more than 90% of patients with Lyme disease (Irregular expanding annular lesion(s))

* Regional adenopathy, intermittent fevers, headache, myalgias, arthralgia, fatigue, malaise



Stage 2: disseminated/ secondary



* Days to weeks after tick bite

* Intermittent fluctuating sx that eventually resolve

* Triad of aseptic meningitis, cranial neuritis, and radiculoneuritis: bell palsy most common

* Cardiac symptoms: tachycardia, bradycardia, AV block, myopericarditis



Stage 3: tertiary/ late



* Symptoms occur >1 year after tick bite

* Acrodermatitis chronic atrophicans: Atrophic lesions on extensor surfaces of extremities (resembles scleroderma)

* Monoarthritis, oligoarthritis (knee > shoulder > elbow)

* GI: Hepatitis, RUQ pain

* Ocular: keratitis, uveitis, iritis, optic neuritis

* Neurological: Chronic axonal polyneuropathy or encephalopathy



Chronic Lyme disease (versus well-accepted Lyme disease sequelae):



* Continuation of symptoms after antibiotics

* Current recommendation for management is supportive care only



Pediatric considerations:



* More likely to be febrile than adults

* Facial palsy accompanied by aseptic meningitis in 1/3

* Untreated kids can develop keratitis

* Excellent prognosis if appropriately treated



History



* Travel, camping, woods, playing under leaves or in wood piles

* Living in endemic area (Northeastern area: Maine to Virginia; upper Midwestern: Wisconsin, Minnesota; Northwest California)

* Endemic in Northern Europe and Eastern Asia as well

* History of tick bite (- 30-50% of patients recall tick bite)

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